Hydrodynamic bearing applied on a contact interface of a fluid compressor based on a spiral type mechanism

ABSTRACT

This invention refers to a hydrodynamic bearing applied on a contact interface of a fluid compressor based on a spiral type mechanism. The aforesaid hydrodynamic bearing is located in the contact interface between the lower face of the orbiting whorl and the upper face ( 11 ) of the block ( 1 ), and comprises at least two regions ( 2 ) spaced apart between regions ( 3 ). The regions ( 2 ) have surfaces comprised of a plurality of micro-cavities ( 21 ) and the regions ( 3 ) have substantially smooth surfaces.

FIELD OF THE INVENTION

This invention refers to a hydrodynamic bearing applied on a contactinterface of a fluid compressor based on a spiral type mechanism and,more particularly, a thrust bearing that is specially texturized(partial texturization) applied on the contact interface between theblock and the non-orbiting whorl of a fluid compressor based on a spiraltype mechanism.

The aforesaid partial texturization of the revealed hydrodynamic bearingis especially capable of acting as a reservoir of lubricating fluid andas a deposit of possible abrasive particles produced from the wear ofother elements of the fluid compressor based on the spiral typemechanism.

FOUNDATIONS OF THE INVENTION

It is well-known to specialists versed in the subject matter that fluidcompressors based on a spiral type mechanisms, or scroll compressors,comprise of fluid compression devices, whose mechanism is based on aconceptual technology initially published in 1905 and, moreparticularly, published in patent document U.S. Pat. No. 801,182.

According to this document, a spiral type mechanism comprises of twosimilar structures (circular plates with a perpendicular wall that has afundamentally spiral outline) inversely coupled together (where the topof one perpendicular wall of a fundamentally spiraled outline of onecircular plate is turned to the base of another circular plate, beingthe true reciprocal) through a coupling. Moreover, one of thesestructures is also attached to an electric motor.

The structure attached to the electric motor is denominated the orbitingwhorl and the other structure is denominated the fixed whorl.

According to the fundamental principles described in document U.S. Pat.No. 801,182, the means of coupling used between the orbiting whorl andthe fixed whorl comprises of an element that is capable of providing theorbiting whorl with an orbital movement from the rotational movement ofthe shaft of the electric motor. Therefore, and according to thisconcept, the orbital movement of the orbiting whorl, in relation to thefixed whorl, results in allowing that the spiraled perpendicular wall ofthe orbiting whorl alters, continuously and gradually, the points ofcontact between its lateral face and the lateral face of the fixedwhorl. This continuous and gradual alteration between these points ofcontact of spiraled perpendicular walls produces continuously decreasingchambers. Because these virtual chambers can be filled with diversefluids, the possibility of the compression of these diverse fluids cantake place.

Generally, the spiral type mechanism and the electric motor are attachedin the interior of the same housing (normally hermetic), and, therefore,it is common to fix them, one to the other, through a rigid structure,which is known as a compressor block.

Accordingly, the conventional embodiments of fluid compressors based onspiral type mechanisms establish multiple contact interfaces between themoving sections and the fixed sections. Among these contact interfacesis emphasized the contact interface between the shaft of the motor andthe piping of the block, the contact interface between the tops andbases of the orbiting and fixed whorls, and the contact interfacebetween the lower face of the orbiting whorl and the upper face of theblock.

Generally, and according to the traditional teaching of the state of theart, these contact interfaces use hydrodynamic bearings, i.e. “chambers”of lubricating fluids are used between the contact interfaces. Thesehydrodynamic bearings have the main objective to reduce the contact and,consequently, the attrition between the elements that define thepreviously mentioned contact interfaces.

The current state of the art comprises of an infinite number of patentdocuments that describe concepts and optimizations applied onhydrodynamic bearings, in addition to lubrication systems of thesebearings.

With respect to embodiments of fluid compressors, especially fluidcompressors based on a spiral type mechanism, it is common to note thatthe lubricating fluid that is responsible for the lubrication of all thebearings is stored in the interior of the hermetic housing of thecompressor. It is conducted to the aforesaid bearings through the shaftof the electric motor from the moment when the compressor is started up,and returns afterwards to the “bottom” of the hermetic housing due tothe action of gravity.

In this regard, it is observed that in these embodiments the lowerbearings are lubricated before the upper bearings. This signifies thatsome of the contact interfaces that use hydrodynamic bearings are latein relation to the starting up of the compressor, entering into directcontact after a few seconds.

It is observed that, during the useful life of these compressors,certain contact interfaces tend to be more worn than other contactinterfaces. For example, it is noted that the contact interface betweenthe lower face of the orbiting whorl and the upper face of the blocktend to wear quicker than the contact interface between the shaft of themotor and the piping of the block. The latter uses hydrodynamic bearingswith a time interval that is less than the time interval that the formeruses hydrodynamic bearings.

This aspect characterizes a significant negative aspect. The establisheduseful lives are different for the contact interfaces of the samecompressor. Therefore, the same compressor can be replaced (or submittedto maintenance) when part of its components are still preserved.Alternatively, the same compressor could be continually used with partof its components damaged.

However, the current state of the art also provides embodiments that arespecially designed to resolve the abovementioned negativecharacteristic.

Examples of these embodiments can be found in the documents U.S. Pat.No. 7,329,109 and JP 2002213374.

Document U.S. Pat. No. 7,329,109 describes a fluid compressor based on aspiral type mechanism whose contact interface between the tops and basesof the orbiting and fixed whorls provides at least one retention recessof oil formed in at least one of these components. The aforesaidretention recess of oil is constructed in a manner to preserve aquantity of oil capable of providing the hydrodynamic bearing betweenthese components at the same time when the compressor is started up.Moreover, this hydrodynamic “chamber” also acts as a seal between thewhorls.

Document JP 2002213374 describes a fluid compressor based on a spiraltype mechanism whose upper face of the whorl provides a plurality ofconcavities that optimize the hydrodynamic bearing of the contactinterface between the tops and bases of the orbiting and fixed whorls.Perceptibly, the objectives of this embodiment are similar to theobjectives of the embodiment described in document U.S. Pat. No.7,329,109.

There are further examples of embodiments, pertaining to the currentstate of the art, which attempt to resolve, or at least mitigate, thepreviously cited negative characteristics. Of special interest to theinvention in question are the embodiments described in documents U.S.Pat. No. 6,537,045 and U.S. Pat. No. 7,422,423.

Document U.S. Pat. No. 6,537,045 describes a fluid compressor based on aspiral type mechanism whose contact interface between the lower face ofthe orbiting whorl and the upper face of the block provides multiplerecesses of micrometric depth (from 30 μm to 150 μm). These arespecially designed for the optimization of the hydrodynamic bearing ofthe aforesaid contact interface. These recesses also have the objectiveto act as pre-reservoirs of lubricating fluid and are supposedly capableof preserving a quantity that is capable of promoting the hydrodynamicbearing between these components at the same time when the compressor isstarted up.

In any event, the depth of the multiple recesses described in documentU.S. Pat. No. 6,537,045 is too large. It does not allow for the creationof a field of pressure that is necessary to provide support for theload. This is because in films of oil with the special viscosity for theScroll type compressors (ISO 10 to ISO 68), the “height” of the film ofoil (in a hydrodynamic setting) is fundamentally defined by the maximumdepth of the recesses. When this depth is large, the “height” of thefilm of oil produces a fundamentally null “support pressure”, asascertained through the basic precepts of the classic theory oflubrication.

Document U.S. Pat. No. 7,422,423 describes an alternative compressorused in refrigeration systems. The aforesaid compressor provides aplurality of “contact sections” that exist between the moving parts ofthe compressor. In particular, the “contact sections” are sphericalshaped recesses, which are configured to cause a vortex flow of the oilretained therein. It is also noted that the aforementioned sphericalrecesses are shaped through grinding by machining. Furthermore, theteaching described in document US 7422423 is especially efficient whenapplied on hydrodynamic bearings where there is a rotational oralternating movement. However, embodiments are not produced that areespecially dedicated to hydrodynamic bearings where there is orbitalmovement.

Based on the context explained above, it is evident that there is a needfor the development of a solution capable of optimizing the hydrodynamicbearing of contact interfaces, where there is orbital movementparticularly between elements that form part of fluid compressorsespecially based on spiral type mechanisms.

OBJECTIVES OF THE INVENTION

Accordingly, it is one of the objectives of this invention to produce ahydrodynamic bearing applied on a contact interface of a fluidcompressor based on a spiral type mechanism capable of optimizing thehydrodynamic bearing of the contact interface between the lower face ofthe orbiting whorl and the upper face of the block.

It is also one of the objectives of this invention to disclose ahydrodynamic bearing applied on a contact interface of a fluidcompressor based on a spiral type mechanism capable of producing theeffect known as an equivalent “Rayleigh step”, for the conjoined effectof the partially texturized micro-cavities.

It is also one of the objectives of this invention that the hydrodynamicbearing applied on a contact interface of a fluid compressor based onthe disclosed spiral type mechanism shall also be capable of shapingdeposits for the abrasive particles produced from the wear of theinternal components of the compressor during its entire life, removingthem from the contact between the involved surfaces, thereby promotingless associated wear.

SUMMARY OF THE INVENTION

These and other objectives of the disclosed invention are totallyobtained by means of the hydrodynamic bearing applied on a contactinterface of a fluid compressor based on a spiral type mechanism.

According to the principles and objectives of this invention, thecompressor comprises of at least one hermetic housing, at least oneelectric motor, at least one block, at least a spiral type mechanismcomprising of at least one orbiting whorl and at least one non-orbitingwhorl.

Also according to the principles and objectives of this invention, thehydrodynamic bearing, which is located in the contact interface betweenthe lower face of the orbiting whorl and the upper face of the block,comprises of at least two regions having surfaces comprising of aplurality of micro-cavities spaced apart by regions having substantiallysmooth surfaces.

Among the possible embodiments of the invention in question, it isemphasized that the abovementioned regions can be defined on the lowerface of the orbiting whorl or the upper face of the block. They can alsobe simultaneously defined on the lower face of the orbiting whorl andthe upper face of the block.

In this regard, it is evident that the sum of the regions withmicro-cavities corresponds from 30% to 80% of the area where they arelocated. The aforesaid micro-cavities also comprise of deposits ofabrasive particles.

It is emphasized that the micro-cavities have original specifications.In this regard, each micro-cavity has a depth of between 1 μm to 30 μm,a surface area of between 5 μm to 100 μm, and a border radius of between0.01 μm to 30 μm. Furthermore, and preferentially, the micro-cavities(31) are spaced apart by a distance of between 1 μm to 100 μm.

It is also observed that the aforesaid micro-cavities comprise of asurface area that has a circular, elliptical or even rectangularprofile. In this latter case, each micro-cavity with a surface area thathas a rectangular profile comprises of micro-channels.

Optionally, it is also mentioned that at least one radial channel islocated in at least one of the substantially smooth surface regions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention in question will be described in detail based on thefigures listed below, as follows:

FIG. 1 illustrates, in an isometric perspective, a fluid compressorblock based on a spiral type mechanism, according to the preferentialembodiment of this invention; and

FIG. 2 illustrates an amplified detail taken from FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

According to the physical concepts amply studied by the specialists inthe subject matter and especially according to the classical theory oflubrication, it is known that the concept “Rayleigh step” concerns theproduction of hydrodynamic pressure, or support pressure, in alubrication fluid located between two moving bodies. In this regard,when there is a physical step between two surfaces in relative movement,and separated by a fluid with appropriate viscosity, a “maximum” occursin the gradient of the hydrodynamic pressure, which contributessignificantly to the efficiency of the lubrication.

It is observed that the “texturization” (conjoining of recesses) definedin the bearings exemplified in documents U.S. Pat. No. 6,537,045 andU.S. Pat. No. 7,422,423 do not obtain this effect. The simple spacebetween the recesses is incapable of configuring an actual physicalstep.

It is in this regard that this invention is emphasized. It discloses aspecially texturized hydrodynamic bearing (applied on a contactinterface of a fluid compressor based on a spiral type mechanism). Thisspecial texturization is, in general terms, from a partialtexturization.

The aforesaid partial texturization is, according to the concepts andobjectives of this invention, applied on a contact interface between theblock and the non-orbiting whorl of a fluid compressor based on a spiraltype mechanism.

This timely solution, up to now inexistent in the current state of theart, is then shaped through the transition from the texturized region tothe non-texturized region, where it forms, due to the difference indepths, a physical step that produces a “maximum” in the fluid pressure.

According to the fundamental concept of the invention in question, onlyone of the faces of the contact interface between the block and thenon-orbiting whorl of a fluid compressor based on a spiral typemechanism requires to be partially texturized. However, both the faces(the block and the non-orbiting whorl) can be partially texturizedwithout this altering the efficiency of the production of the aforesaid“maximum” in the fluid pressure.

In this regard, FIGS. 1 and 2 illustrate the preferential embodiment ofthe invention in question.

Therefore, and according to the preferential embodiment of thisinvention, a hydrodynamic bearing is disclosed (applied on a contactinterface of a fluid compressor based on a spiral type mechanism) whereone of the faces of its composition is partially texturized;

This signifies that the block 1 of the fluid compressor provides on itsupper face 11 six texturized regions 2 and six regions 3 withsubstantially smooth surfaces. However, it is emphasized that thisarrangement/embodiment is only of an illustrative character. In truth,and according to the fundamental concept of the invention in question,it is observed that the sum of the regions 2 corresponds from 30% to 80%of the area where they are located.

Each one of the regions 2 provides a texturization defined by theexistence of a plurality of micro-cavities 21 on its surface.

Preferentially, each micro-cavity 21 has certain dimensionalcharacteristics that are capable of optimizing the creation andmaintenance of a lubricating film from the lubricating oil normally usedin the lubrication of the bearings of the fluid compressors. Thissignifies that the aforesaid micro-cavities 21 act as a type of storagepocket of lubricating oil.

More particularly, it is noted that the dimensional characteristics ofthe micro-cavities 21, as disclosed in this invention, in addition tosupporting the creation and maintenance of the lubricating film, alsoact as deposits of abrasive particles that are produced from the directcontact between the metallic bodies that form part of the fluidcompressor.

Accordingly, each micro-cavity 21 has a depth of between 1 μm to 30 μm,a surface area of between 5 μm to 100 μm and a border radius of between0.01 μm to 30 μm.

It is emphasized that the border radius determines a step in thepressure field. The larger the border radius, the less will be thedifference of pressure in the aforesaid produced pressure field.

Furthermore, it is also verified that the micro-cavities 21 are spacedapart by a distance of between 1 μm to 100 μm. This distance helps tomaintain the lubricating film stable.

It is also observed that, according to the preferential embodiment ofthis invention, the micro-cavities 21 comprise of a surface area thathas a circular profile.

Based on the context described above, it is noted that the regions 2, inthe manner in which they are inserted between regions 3, unify theindividual mechanism of each micro-cavity 21, with their collectiveeffect producing an equivalent convergent effect between the surfaces.This effect is equivalent to the substantial increase of the capacity ofthe load of the lubricating film. The virtual difference between theheights of the surfaces 2 and 3 creates a significant pressure field.

In this regard, and also according to the preferential embodiment of theinvention in question, the sum of the regions 2 corresponds from 30% to80% of the area of the face where they are located.

Optionally, each micro-cavity 21 can also comprise of a surface areathat has an elliptical profile, although this embodiment is notillustrated.

Furthermore, also optionally, each micro-cavity 21 can also comprise ofa surface area that has a rectangular profile, making a micro-channel,which is also capable of optimizing the creation and maintenance of alubricating film, in addition to also acting as a deposit of abrasiveparticles.

Independent of the format and location (on the upper face of the blockof the compressor or on the lower face of the non-orbiting whorl) of themicro-cavities 21, it is disclosed that they can be obtained by several,already known, industrial processes.

Accordingly, the aforesaid micro-cavities 21 are preferentially madethrough grinding using a laser. In this situation, the micro-cavities 21can be specially guided and shaped into almost exact dimensions.

Optionally, the micro-cavities 21 can also be obtained through grindingusing electrolytic machining, or even by electrochemical corrosionwithout masking and other processes that are capable of altering theroughness of metallic surfaces.

Examples of the embodiment of the object of this invention having beendescribed, it should be understood that the scope of the same includesother possible variations, which are limited only by the content of theclaims, including possible equivalent means.

1. A hydrodynamic bearing applied on a contact interface of a fluidcompressor based on a spiral mechanism, the fluid compressor comprising:at least one hermetic housing, at least one electric motor, at least oneblock, at least one spiral type mechanism including at least oneorbiting whorl and at least one non-orbiting whorl; wherein thehydrodynamic bearing is located in the contact interface between a lowerface of the at least one orbiting whorl and an upper face of the atleast one block, the hydrodynamic bearing comprising: at least two firstregions spaced apart between second regions; the at least two firstregions including surfaces having a plurality of micro-cavities; thesecond regions having substantially smooth surfaces; wherein eachmicro-cavity has a depth between 1 μm to 30 μm; wherein eachmicro-cavity has a surface area between 5 μm to 100 μm; wherein eachmicro-cavity has a border radius between 0.01 μm to 30 μm; and whereinthe micro-cavities are spaced apart by a distance between 1 μm to 100μm.
 2. The hydrodynamic bearing, according to claim 1, wherein eachmicro-cavity comprises a surface area having a circular profile.
 3. Thehydrodynamic bearing, according to claim 1, wherein each micro-cavitycomprises a surface area having an elliptical profile.
 4. Thehydrodynamic bearing, according to claim 1, wherein each micro-cavitycomprises a surface area having a rectangular profile.
 5. Thehydrodynamic bearing, according to claim 4, wherein the rectangularprofile of the surface area of each micro-cavity comprisesmicrochannels.
 6. The hydrodynamic bearing, according to claim 1,wherein the at least two first regions and the second regions aredefined on the lower face of the orbiting whorl.
 7. The hydrodynamicbearing, according to claim 1, wherein the at least two first regionsand the second regions are defined on the upper face of the block. 8.The hydrodynamic bearing, according to claim 1, wherein the at least twofirst regions and the second regions are defined simultaneously on thelower face of the orbiting whorl and the upper face of the block.
 9. Thehydrodynamic bearing, according to claim 1, wherein the sum of the atleast two first regions constitutes between 30% to 80% of the area wherethey are located.
 10. The hydrodynamic bearing, according to claim 1,wherein at least one radial channel is located in at least one of thesecond regions.
 11. The hydrodynamic bearing, according to claim 1,wherein the micro-cavities include deposits of abrasive particles.